The SARS virus has been found in sweat glands and the intestine, according to a new study, which says that in theory the disease may spread via contaminated sewage, food or even a handshake, not just by airborne droplets.

Pathologists from the First Military Medical University in Guangzhou, southern China, warned that if further research proved that SARS could be transmitted by these unexpected routes, there would be major implications for public health.

The team devised two ways of testing for the coronavirus (SARS-CoV) that causes severe acute respiratory syndrome.

One was an antibody that binds specifically to the virus, and the other was amplification of telltale fragments of viral DNA.

Using these two markers, they tested tissue from four people who had died of SARS, and from four people who had died of other causes.

As expected, the lungs of people who had died of SARS were riddled with the virus: up to 49% of tissue cells they viewed had been infected.

This is unsurprising because SARS is already known to be a disease that can be carried by droplets expelled in sneezes and coughs, its prime target area is the airways, and its symptoms are similar to pneumonia.

"Strikingly," the authors added, "SARS-CoV was also detected in many other organs and tissues, including stomach, small intestine, distal convoluted renal tubule, sweat gland, parathyroid, pituitary, pancreas, adrenal, liver and cerebrum [brain]."

Viral infection in the small intestine and renal system reached from 25 to 49% of cells, and the same figure was seen for the skin. In the liver, pancreas and brain, 24% or less of cells were infected.

Gastro problems

Lead researcher Dr Ding Yangqing said that, like the respiratory tract, the gastrointestinal system could be "a primary target" for the virus.

"This suggests that the gastrointestinal system may also be an entry route for SARS-CoV [if it is] present in food or water.

"Although there is no report of such transmission, caution should be exercised by the at-risk population during the SARS-CoV endemic season. This finding supports the hypothesis that SARS-CoV may be released into the environment via faeces from individuals" with the disease.

As viral traces were found in the kidneys, urine may also theoretically transmit the disease.

Leaking sewage has been linked with Hong Kong's biggest outbreak of SARS. A total of 321 people, living in 15 blocks in the Amoy Gardens high-rise housing estate in Kowloon, fell sick in March and April last year.

Ding also noted that the virus had, for the first time, been found in sweat gland cells in the skin.

"This suggests another route of transmission for SARS-CoV, since this virus may be excreted in sweat and infect other people who are in direct contact with the patient's skin," he said.

The repercussions for public health may be far-reaching, the study warned.

If, for instance, skin contact is confirmed as a transmission route, it would mean that SARS patients may have to wear gloves, disposable gowns and eye goggles, in addition to a full face mask, to avoid kissing or touching other people.

SARS last year killed almost 800 people worldwide from some 8000 infections, most of them in China and Southeast Asia, before it was halted by quarantine policies. There is still no cure or a vaccine.

In a smaller outbreak linked to handling of the virus in a laboratory, nine people have been diagnosed with the disease in China in the past few weeks, prompting the Chinese authorities to isolate hundreds of people.